Effects Of Combinative Application Of Organic And Chemical Fertilizers On Tomato Growth In Greenhouse And Soil Ecological Environment Factors And Their Relative Mechanism

The long-term phenomenon of irrational fertilization has existed widespreadly in the vegetable production in greenhouse in China,which leads to a lot of soil environmental problems.There are abundant organic fertilizer resources in China,such as animal manures and crop residues,however,the unreasonable deposition not only cause waste of resources but also give rise to environment contamination.With proposing national goal of?reducing the application of chemical fertilizers?and?replacing chemical fertilizers with organic fertilizers?,it is very important and urgent to explore the appropriately combinative application of organic and chemical fertilizers in vegetable production in greenhouse.Based on this,the following studies were carried out with tomato as the experimental vegetable species and chicken manure?CM?,rice husk?RH?and commercial organic fertilizer as the representative organic fertilizers.?1?Experiment of reducing application rate of chemical fertilizer under different chicken manure dosage.The application rate of chicken manure was set as three levels:low?M₁?,medium?M₂?and high?M₃?,which was 15,45 and 75 t hm^-2,respectively.The application rate of chemical fertilizers also was set as three levels:100%conventional rate?F₁?,80%conventional rate?F₂?and 60%conventional rate?F₃?.?2?Experiment of chemical fertilizer repleaced by commercial organic fertilizer with equal nitrogen rate and reduced the application rate of total nitrogen.Four levels of chemical fertilizer nitrogen replaced by organic nitrogen were set and were 20%,40%,60%and 100%,respectively;two levels of reduced total nitrogen were set and were 15%and 30%,respectively.?3?Experiment of mixed application of rice husk and chicken manure in different proportion.Rice husk and chicken manure were mixed according to the mass ratio of 1:0,4:1,2:1 and 0:1.?4?Experiment of the in-situ decomposition and mineralization of organic fertilizers.The in-situ decomposition and mineralization of rice husk,two kinds of mixture and chicken manure in greenhouse were characterized with several high-tech analytical methods.The main results obtained from these researches are as follow.?1?In the greenhouse with low soil nutrient content,the average yield of tomato treated with medium dosage of chichen manure was the highest and were 2.8%and 26.3%higher than low and high dosage of chicken manure,respectively.Chemical fertilizer application rate reduced by 20%and 40%had no significant effect on tomato yield and quality and soil available nutrient content under the condition of all the three dosage of chicken manure in one season.The average soluble sugar content of tomato treated with high chicken manure dosage was by 21.5%significantly lower than that treated with low chicken manure dosage.At the flowering and fruiting stage,compared with the low chicken manure treatment,the content of NO₃^--N,available P and K in surface layer soil?0-20 cm?with high chicken manure dosage treatment significantly enhanced by 169.4%,112.1%and 206.4%,respectively.At the mature stage of the second fruit cluster,compared with the low chicken manure treatment,the content of NO₃^--N,available P and K in surface layer soil?0-20 cm?with high chicken manure dosage treatment significantly enhanced by 12.8%,153.8%and 164.4%,respectively.At the mature stage of the last fruit cluster,compared with the low chicken manure treatment,the content of NO₃^--N,available P and K in surface layer soil?0-20 cm?with high chicken manure dosage treatment significantly enhanced by 105.5%,102.0%and 47.8%,respectively.?2?Compared with conventional fertilization treatment,the yield of tomato with chemical fertilizer N replaced with organic fertilizer N while reduced total N application rate treatment increased by 1.7%¹5.7%.And the larger range of total N reduction was,the higher the yield of tomato obtained.Compared with conventional fertilization treatment,NO₃^--N content of tomato fruit with chemical fertilizer N replaced with organic fertilizer N while reduced total N application rate treatment decreased by 6.0%⁵7.4%and Vc content of tomato fruit increased by 7.1%⁴3.9%,except for 15%reduction of total nitrogen and 60%replacement of chemical fertilizer nitrogen with organic nitrogen treatment and 30%reduction of total nitrogen and 20%replacement of chemical fertilizer nitrogen with organic nitrogen treatment.At the mature stage of the last fruit cluster,compared with conventional fertilization treatment,the content of soil NH₄⁺-N,NO₃^--N and available K with chemical fertilizer N replaced with organic fertilizer N while reduced total N application rate by 15%treatment decrease by 2.2%¹9.8%,0.5%¹7.8%and 10.2%²6.6%,respectively,and the content of available P increased by 4.2%¹5.4%;the content of soil NH₄⁺-N,NO₃^--N and available K with chemical fertilizer N replaced with organic fertilizer N while reduced total N application rate by 30%treatment decreased by 9.3%¹8.6%,4.9%²5.7%and 11.2%²6.6%,respectively,and the content of available P content increased by 7.0%²4.4%.Compared with conventional fertilization treatment,the amounts of leaching loss of soil inorganic N with 15%reduction of total nitrogen and 40%replacement of chemical fertilizer nitrogen with organic nitrogen treatment and 30%reduction of total nitrogen and 40%replacement of chemical fertilizer nitrogen with organic nitrogen treatment decreased by 21.1%and 26.0%,respectively during the whole growth period.?3?The yield of tomato with Mixture 2?Mix2?treatment was the highest in three consecutive seasons.In the early spring season of 2018,compared with prior soil,the content of NO₃^--N in surface soil with RH,Mix1 and Mix2 treatment at the middle flowering and fruiting stage?one month after application of base fertilizer?decreased by 86.3%,55.1%and62.0%,respectively,and soil NO₃^--N content with CM treatment increased by 191.9%;and the content of soil NO₃^--N with CM treatment was significantly higher than that with RH,Mix1 and Mix2 treatments.In the early spring season of 2018,NO₃^--N content in the soil layer of 0-100 cm with CM treatment was significantly higher than RH,Mix1 and Mix2treatment at the mature stage of the last fruit cluster.In the early spring season of 2019,NO₃^--N content in 20-100 cm soil layer with CM treatment was still significantly higher than in RH,Mix1 and Mix2 treatment at the mature stage of the last fruit cluster,but the NO₃^--N content in surface soil with RH,Mix1 and Mix2 treatment was 14.0%,16.9%and 31.9%higher than CM treatment,respectively.Under topdressing nitrogen fertilizer in the early spring season of 2018,the soil N₂O emission flux of each treatment was the largest on the first day after irrigation,and CM treatment was significantly higher than RH,Mix1 and Mix2treatment.With the increase of days after irrigation,the soil N₂O emission flux of each treatment declined dramatically.Under nitrogen fertilizer topdressing free,the soil N₂O emission flux of each treatment enhanced gradually with the increase of days after the irrigation.In the early spring season of 2019,compared with CM treatment,soil porosity with RH,Mix1 and Mix2 treatment increased significantly and soil bulk density and hardness decreased significantly at the mature stage of the last fruit cluster.?4?With the incubation period increase,the organic carbon content,hemicellulose content,cellulose content and lignin content of rice husk,mixture 1 and mixture 2 showed a trend,that rised and then declined.Content of organic nitrogen enhanced slowly at first,and the rate of enhancement increased obviously at the later stage,especially after 241 days.The organic carbon content,organic nitrogen content,hemicellulose content and cellulose content of chicken manure declined rapidly during the early stage,and the rate of decline significantly slowed down during the later stage.The polyphenol content of the four kinds of organic fertilizer declined considerably on the 7th day,and then the declining rate of rapidly reduced and tended stable with the increase of time.After 334 days in-situ incubation,the mineralization ratios of rice husk,mixture 1,mixture 2 and chicken manure were-22.3%,-2.4%,12.5%and 48.8%,respectively.The cumulative mineralization ratio of organic carbon and the cumulative decomposition ratios of polyphenol,hemicellulose,cellulose and lignin of rice husk and two kinds of mixture enhanced rapidly in the first 29 days,and remained no obvious change in the middle period and significantly enhanced in the later period.The cumulative mineralization ratio of organic carbon and the cumulative decomposition ratios of polyphenol,hemicellulose,cellulose and lignin of chicken manure also increased fastly in the first 29 day,and then increased slowly until the end of the experiment.The content of ready degradable O-alkyl-C in both original sample and sample incubated for 334 days of rice husk and two kinds of mixture was much higher than the content of other types of organic carbon.The content of O-alkyl-C was the highest in the original chicken manure samples but the content of recalcitrant alkyl-C was the highest in the chicken manure sample incubated for334 days.In short,when chicken manure was applied to the soil,it could be rapidly decomposed and released a large number of nutrient ions,which gave rise to increase greatly the content of soil available nutrient.The application of rice husk stimulated the strong biological immobilization of available nitrogen,which led to the rapid decrease of soil NO₃^--N content and the significant increase of organic nitrogen content in rice husk.Compared with the chicken manure+chemical fertilizer model,rice husk+chicken manure+chemical fertilizer model can significantly reduce the content of NO₃^--N in the subsoil.High dosage of chicken manure combined with chemical fertilizer enhanced the risk of reducing the yield of tomato.Mixing chicken manure and rice husk in the ratio of 1:2 by mass and then combining with chemical fertilizer can keep stably soil available nitrogen supply,and improve the physical properties of the soil and increase the yield of tomato.On the premise of high soil basic fertility,organic fertilizer replacing chemical fertilizer can increase the yield of tomato,and improve the quality of tomato fruit,and lower the loss of soil inorganic nitrogen by leaching and promote the green development of vegetable production in greenhouse.